Dynamical Analysis of Drug Efficacy and Mechanism of Action Using GFP Reporters

To the development of effective cancer drug, it is necessary to, first, identify drugs and their possible combinations that could exert desired control over the type of cancer being considered; second, have a drug testing method that allows one to assess the variety of responses that can be provoked by drugs. To facilitate such an experiment-modeling-experiment cycle for drug development, a method based on the dynamical systems of pathways is presented. It involves a three-state experimental design: (1) formulate an oncologic pathway model of relevant cancer; (2) perturb the pathways with the drugs of known effects on components of the pathways of interest; and (3) measure process activity indicators at various points on cell populations. To evaluate the drug response in a high-throughput manner, a green fluorescent protein reporter-based technology has been developed. The authors apply the dynamical approach to several issues in the context of colon cancer cell lines.

Assessing Combinational Drug Efficacy in Cancer Cells by Using Image-based Dynamic Response Analysis

The landscape of translational research has been shifting toward drug combination therapies. Pairing of drugs allows for more types of drug interaction with cells. In order to accurately and comprehensively assess combinational drug efficacy, analytical methods capable of recognizing these alternative reactions will be required to prioritize those drug candidates having better chances of delivering appreciable therapeutic benefits. Traditional efficacy measures are primarily based on the “extent” of drug inhibition, which is the percentage of cells being killed after drug exposure. Here, we introduce a second dimension of evaluation criterion, speed of killing, based on a live cell imaging assay. This dynamic response trajectory approach takes advantage of both “extent” and “speed” information and uncovers synergisms that would otherwise be missed, while also generating hypotheses regarding important mechanistic modes of drug action.

Tracking transcriptional activities with high-content epifluorescent imaging

High-content cell imaging based on fluorescent protein reporters has recently been used to track the transcriptional activities of multiple genes under different external stimuli for extended periods. This technology enhances our ability to discover treatment-induced regulatory mechanisms, temporally order their onsets and recognize their relationships. To fully realize these possibilities and explore their potential in biological and pharmaceutical applications, we introduce a new data processing procedure to extract information about the dynamics of cell processes based on this technology. The proposed procedure contains two parts: (1) image processing, where the fluorescent images are processed to identify individual cells and allow their transcriptional activity levels to be quantified; and (2) data representation, where the extracted time course data are summarized and represented in a way that facilitates efficient evaluation. Experiments show that the proposed procedure achieves fast and robust image segmentation with sufficient accuracy. The extracted cellular dynamics are highly reproducible and sensitive enough to detect subtle activity differences and identify mechanisms responding to selected perturbations. This method should be able to help biologists identify the alterations of cellular mechanisms that allow drug candidates to change cell behavior and thereby improve the efficiency of drug discovery and treatment design.

Abstract LB-277: Dynamic functional analysis of the response of cancer cell lines to the drug UNBS1450

The analysis of the dynamics of cellular responses to drugs is currently bounded by inherent limitations of the methods most often used to assess levels of promoter activity and protein abundance or activation. The sensitivity of these assays is limited by the averaging of analyte over many cells, which can produce an average that is not accurately descriptive of the wide range of activities of members of the population examined. The ability of these assays to indicate the trajectory of the various responses is limited by a very infrequent sampling rate, frequently 2–4 time points spread over many hours. These limits are further exacerbated by populations of treated cells' inhomogeneity in the timing of their own response to the drugs. To improve the determination of the functional dynamics of cells' responses to drugs, PBS-Bio has developed technology that allows gathering data from living cells using fluorescent reporter technology. This technology allows measurements to be made serially on single populations of cells at the individual cell level, providing both high sensitivity in terms of when even a small fraction of the cells exhibit significant shifts of a particular activity, the rate of shift of cells in the population to this different activity and the ability to temporally order the timing of events relative to each other. Experimentation on two cell lines, A549 and PC3, using a variety of drugs that affect different cellular processes and a set of fluorescent reporters that provide information on a variety of cellular processes it was possible to show that the modified cardenolide drug, UNBS1450 (Unibioscreen), provoked a very early reduction in the expression of the MCL1 and MYC genes, followed by induction of a strong apoptotic response in both cell lines. As loss of MCL1 provoked by other means has been shown to be sufficient to induce apoptosis in both these lines, a very strong case can be made for UNBS1450's ability to provoke Mcl1 protein reduction as the drug's mode of apoptotic induction. This finding would also implicate Mcl1 as a useful biomarker of the possible efficacy of UNBS1450.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-277. doi:10.1158/1538-7445.AM2011-LB-277